Fluidic adaptive lens systems and methods

ABSTRACT

Fluidic adaptive lens devices, and systems employing such lens devices, along with methods of fabricating and operating such lens devices, are disclosed. In one embodiment, a lens material is optimally selected to provide one or more desired characteristics for a variety of applications related to adaptive lens devices. In another embodiment, a fluidic medium is optimally chosen to provide one or more desired characteristics for a variety of applications related to adaptive lens devices.

PRIORITY

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/683,141 entitled “Fluidic Adaptive Lens Systems and Methods”filed on Mar. 7, 2007 now U.S. Pat. No. 7,453,646, which is acontinuation-in-part of U.S. patent application Ser. No. 10/599,486filed on Mar. 3, 2005, now U.S. Pat. No. 7,675,686 which is the U.S.national phase patent application of International Application No.PCT/US05/10948 entitled “Fluidic Adaptive Lens” filed on Mar. 31, 2005,and which claims priority to U.S. provisional application No. 60/558,293entitled “Fluidic Adaptive Lens” filed on Mar. 31, 2004, each of whichis hereby incorporated by reference herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with United States Government support awarded bythe following agencies: Defense Advanced Research Projects Agency(DARPA) Grant No. F49620-02-1-0426; and Air Force Office of ScientificResearch (AFOSR) Grant No. F49620-02-1-0426. The United StatesGovernment has certain rights in this invention.

FIELD OF THE INVENTION

The present invention relates to optical lenses. In particular, but notby way of limitation, the present invention relates to vision correctionlenses, microscopes, zoom lens systems, and cameras, such as areemployed in various optical systems.

BACKGROUND OF THE INVENTION

Optical lenses are employed in a variety of devices for many purposessuch as modifying focus and magnification. Many conventional devicesthat employ optical lenses use lenses that are made from solidmaterials, such that the optical properties of the lenses (e.g., theirfocal distances) remain constant or nearly constant over time. Forexample, eyeglasses used for vision correction typically are made ofsolid materials such as glass and plastic. Similarly, cameras and otheroptical systems such as microscopes, video monitors, video recorders,copy machines, scanners, etc., commonly employ solid lenses.

Although lenses made from solid materials generally maintain theiroptical properties over time, the use of such lenses also has numerousdisadvantages. With respect to vision correction lenses, for example,the power of vision correction is fixed at the time of fabrication ofthe lenses. As a consequence, today's eyeglass lenses often cannot bemass produced at low cost because the lenses are specially fabricatedfor each and every patient. Since each patient has his/her unique powerrequirement for eye correction, the patient has to see anophthalmologist or optometrist to measure his/her eye correction powerfirst before having the vision correction lenses fabricated. Inaddition, machining glass or plastic material to the precise shape of alens according to a prescription is, by itself, a relatively high-costand low throughput process. Often, it takes several days or even weeksfor patients to receive a new pair of eyeglasses. In comparison withcertain off-the-shelf vision products such as sunglasses,vision-correcting eyeglasses designed and fabricated using currenttechnology are particularly expensive and complicated to manufacture.

Further, vision correction lenses used in today's eyeglasses do not havethe flexibility to handle various situations with which wearers areoften confronted. For example, the optimal eye correction for a givenindividual frequently varies depending upon a variety of factors, suchas the person's age, the person's lifestyle, and various practicalcircumstances. Consequently, an adult typically needs to replace his orher eye correction lenses every few years. For juveniles or adolescents,updating of vision correction eyeglasses often is required morefrequently than for adults.

For certain persons, particularly persons in their 50s and over, thevision correction that is needed for viewing near objects can be verydifferent from the vision correction that is needed for viewing distantobjects. To provide different levels of vision correction via a singlepair of eyeglasses, many of today's eyeglasses employ bifocal lenses (oreven tri-focal or otherwise multi-focal lenses), in which differentsections of a given lens provide different optical properties. Yet suchbifocal lenses offer at best an inconvenient solution to the problem ofhow to provide varying levels of vision correction on a single pair ofeyeglasses. Traditionally, bifocal lenses are formed from pairs of lensportions that are positioned or fused adjacent to one another along amidline of the overall lens. Because the midline between the lensportions is a perceptible boundary between the lens portions, suchlenses are often cosmetically undesirable.

Although newer bifocal lenses are available that are not as cosmeticallyundesirable, insofar as the lenses are graded such that there is only agradual change of correction power from region to region on the lens andsuch that a clear boundary separating different regions of the lens doesnot exist, such newer bifocal lenses nevertheless share other problemswith traditional bifocal lenses. In particular, because differentportions of the lenses have different vision correction characteristics,the wearer's field-of-view at any given time or circumstance via thelenses is still compromised insofar as only certain portions of thelenses provide the appropriate optical characteristics for the wearer atthat time/circumstance.

Additionally, while many persons do not require bifocal lenses, thesepersons can nevertheless prefer that their eyeglasses provide differentamounts of vision correction in different situations. For example, thepreferred amount of vision correction for a person when driving a car orwatching a movie can differ from the preferred amount of visioncorrection for that person when reading a book or working in front of acomputer screen.

For at least these reasons, therefore, it is apparent that the use ofsolid lenses with fixed optical properties in eyeglasses isdisadvantageous in a variety of respects. Yet the disadvantagesassociated with using solid lenses with fixed optical properties are notlimited to the disadvantages associated with using such lenses ineyeglasses/eyewear. Indeed, the use of solid lenses with fixedproperties in a variety of devices such as cameras, microscopes, videomonitors, video recorders, copy machines, scanners, etc. also presentssimilar disadvantages.

Further, the use of solid lenses with fixed optical properties entailsadditional disadvantages in systems that employ combinations of lensesthat interact with one another to provide overall optical properties.Such systems include, for example, zoom lens systems in which two ormore optical lenses of fixed optical properties are moved relative toone another to change optical properties of the overall combination oflenses forming the zoom lens. Because the optical properties of theindividual lenses used in such systems are fixed, the overall opticalproperties of the combinations of lenses depend upon other factors,particularly the relative positioning of the individual lenses.Consequently, to provide the desirable features and capabilitiesassociated with systems such as zoom lens systems, complicated andexpensive mechanical and/or other components and techniques must beemployed to achieve the desired effects.

In particular with respect to zoom lens systems, conventional systemswith zooming capabilities are typically more expensive and often morebulky/heavy than systems without such capabilities. The most importantfigure of merit for zoom lenses is the zoom ratio. The higher the zoomratio is, the more costly the system becomes. A typical camera has anoptical zoom ratio of about 3, and some high-end imaging systems have azoom ratio of greater than 10. Currently, all optical zoom lensesachieve zoom-in and zoom-out functions by changing the distance(s)between the individual lenses forming the overall zoom lens. Thisinvolves high-precision mechanical motions of the lenses over a typicalrange of several centimeters. To provide highly-precise, reliablerelative movement of the lenses typically requires a mechanical systemthat is complicated, slow, bulky and expensive.

The need to vary lens distance to achieve zooming has become a roadblockfor incorporating zooming features into many new and emergingapplications. Many modern “electronic gadgets” including cell phones,personal digital assistants (PDAs), and notebook computers are equippedwith CCD or CMOS cameras. Implementation of cameras into such gadgetshas evolved from being a novelty to being a standard feature, and manysuch gadgets now support imaging-related functions that involve not justimaging but also recording, videophone capabilities, and videoconferencing. Yet conventional zoom lenses are difficult to incorporateinto these small electronic gadgets and their optical devices.

Therefore, it would be advantageous if one or more new types of lensesand/or lens systems could be developed that alleviated the disadvantagesassociated with using solid lenses having fixed optical properties asdiscussed above. In particular, it would be advantageous if a new typeof lens or lens system could be developed for implementation ineyeglasses that made it possible to easily and inexpensively adjustoptical characteristics of the eyeglasses without entirely replacing thelenses. It would further be advantageous if the optical characteristicsof the lenses could be flexibly varied over a wide spectrum, rather thansimply to a limited number of discrete levels. It additionally would beadvantageous if variations in the optical properties of a lens could beapplied to the entire lens, so that, for example, variations in theoptical properties of the lens would apply to an entire range of visionof a wearer of eyeglasses employing the lens, rather than merely aportion of that range of vision.

It further would be advantageous if the new type of lens or lens systemcould also or alternatively be implemented in other systems that employlenses such as cameras, microscopes, video monitors, video recorders,optical recording mechanisms, surveillance equipment, inspectionequipment, agile imaging equipment, target tracking equipment, copymachines, scanners, etc. It additionally would be advantageous if thenew type of lens or lens system could be implemented in zoom lenssystems in a manner that reduced the need for complicated mechanicalsystems for controlling relative positioning of multiple lenses withinthe zoom lens systems. It also would be advantageous if a zoom lenssystem employing the new type of lens or lens system could be compactlyimplemented on one or more types of physically small “electronicgadgets” such as cell phones, personal digital assistants (PDAs), ornotebook computers.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention that are shown in thedrawings are summarized below. These and other embodiments are morefully described in the Detailed Description section. It is to beunderstood, however, that there is no intention to limit the inventionto the forms described in this Summary of the Invention or in theDetailed Description. One skilled in the art can recognize that thereare numerous modifications, equivalents and alternative constructionsthat fall within the spirit and scope of the invention as expressed inthe claims.

The present inventor has recognized that many of the above-mentioneddisadvantages associated with conventional eyeglasses and opticalsystems, including systems employing multiple lenses such as zoom lenssystems, can be alleviated or eliminated if the eyeglasses or opticalsystems employ lenses that are variable or adaptive in terms of theiroptical properties. The present inventor further has discovered thatlenses having adaptive optical properties can be formed through the useof one or more optically transparent flexible diaphragms/membranes thatrespectively separate pairs of fluidic media. By appropriately varyingone or more of the pressures of the fluidic media, which results inchanges in the positioning of the membranes and the amounts of one ormore of the respective fluidic media through which light passes, theoptical properties of the lenses can be varied.

In particular, the present invention in at least some embodiments canprovide a lens device that includes a first partition that is flexibleand optically transparent and a second partition that is coupled to thefirst partition, where at least a portion of the second partition isoptically transparent, and where a first cavity is formed in between thefirst partition and the second partition. The lens device can furtherinclude a first fluidic medium positioned within the cavity, the fluidicmedium also being optically transparent, and a first component capableof controlling a parameter of the fluidic medium. When the parameter ofthe fluidic medium changes, the first partition flexes and an opticalproperty of the lens is varied.

In at least some embodiments, the present invention can also provide amulti-lens apparatus comprising a first fluidic adaptive lens, a secondfluidic adaptive lens, and an intermediate structure coupling the firstand second fluidic adaptive lenses, where the intermediate structure isat least partly optically transparent.

Additionally, in at least some embodiments, the present invention canprovide a method of fabricating a fluidic adaptive lens device. Themethod can include providing a first structure having a first cavity,where the first cavity is only partially enclosed by the firststructure, and attaching a first flexible layer and the first structureto one another in a manner that substantially encloses the first cavity.The first cavity is capable of being filled with a first fluid so thatthe first structure, first flexible layer, and first fluid interact toform the fluidic adaptive lens device.

Also, in at least some embodiments, the present invention can provide amethod of operating a lens device. The method can include providing alens structure including a flexible layer and a rigid structure coupledto one another and forming a cavity, and adjusting a fluid pressure offluid within the cavity so as to adjust a flexure of the flexible layer.

The present inventor has recognized the desirability of providingoptimized components and/or materials for use in fluidic adaptivelenses. More particularly, the present inventor has recognized thedesirability of providing fluidic adapted lenses with optimally selectedlens fluid that provides certain desired characteristics including, forexample, a relatively high index of refraction, a low attenuation overthe wavelength spectrum of interest, a relatively high transmission overa relatively large wavelength spectrum of interest, a relatively hightransmission over a relatively small wavelength spectrum of interest, awide range of operable temperature, a wide range of storage temperature,an extremely low (nearly zero) vapor pressure, and/or a chemicalstability with lens membrane and chamber material.

The present inventor has further recognized the desirability ofproviding fluidic adapted lenses with optimally selected lens membranematerial that provides certain desired characteristics including, forexample, high flexibility and/or reasonably low spring constant.

Therefore, in at least some embodiments, the present invention relatesto a lens device that includes a lens chamber including a plurality ofsurfaces, where at least one surface of the plurality of surfaces isoptically transparent, and a lens membrane coupled to the lens chamber,where at least a portion of the lens membrane is flexible and opticallytransparent, and where the lens membrane and the lens chamber define afirst cavity. The lens device further includes a fluidic mediumpositioned within the first cavity, the fluidic medium also beingoptically transparent, and a control device capable of controlling aparameter of the fluidic medium. In at least some such embodiments, thefluidic medium can be/include any of a variety of fluids including, forexample, polyphenyl ether (“PPE”), thioethers benzene, lens fluid LS5257available from Nusil Technology LLC of Carpinteria, Calif., a lens oil,a fluid containing at least one phenyl group, and/or a fluid having amolar molecular weight greater than 200 g.

Also, in at least some embodiments, the present invention relates to amethod of fabricating a fluidic adaptive lens device. The methodincludes providing a lens chamber including a plurality of surfaces,where at least one surface of the plurality of surfaces is opticallytransparent, and affixing a lens membrane to the lens chamber, where atleast a portion of the lens membrane is flexible and opticallytransparent and where the lens membrane and the lens chamber define afirst cavity. The method additionally includes positioning a fluidicmedium within the first cavity, where the fluidic medium is opticallytransparent, and providing a control device capable of controlling aparameter of the fluidic medium. Again, the fluidic medium can take anyof a variety of forms depending upon the embodiment.

Further, in at least some embodiments, the present invention relates toa lens system. The lens system includes first and second lensstructures. Each of the first and second lens structures includes arespective lens chamber including a respective plurality of surfaces,where at least one surface of the respective plurality of surfaces ofeach respective lens chamber is optically transparent. Also, each of thefirst and second lens structures includes a respective lens membranecoupled to the respective lens chamber of each respective lensstructure, where at least a portion of each respective lens membrane isflexible and optically transparent, and where the respective lensmembrane and the respective lens chamber of each respective lensstructure together define a respective cavity. Further, the lens systemincludes at least one fluidic medium positioned within the cavities ofthe first and second lens structures, the at least one fluidic mediumalso being optically transparent, and means for controlling at least oneparameter of the at least one fluidic medium.

As previously stated, the aforementioned embodiments andimplementations, and embodiments described below, are for illustrationpurposes only. Numerous other embodiments, implementations, and detailsof the invention are easily recognized by those of skill in the art fromthe following description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Various objects and advantages and a more complete understanding of thepresent invention are apparent and more readily appreciated by referenceto the following Detailed Description and to the appended claims whentaken in conjunction with the accompanying drawings wherein:

FIG. 1 a shows, in simplified schematic form, a cross-sectional view ofone embodiment associated with a fluidic adaptive lens of the presentinvention;

FIG. 1 b shows, in simplified schematic form, a cross-sectional view ofone embodiment associated with a fluidic adaptive lens of the presentinvention;

FIG. 2 shows a pair of eyeglasses within which fluidic adaptive lensesare employed of the present invention;

FIGS. 3 a and 3 b show, in simplified schematic form, cross-sectionalviews of a convex fluidic adaptive lens and a concave fluidic adaptivelens, respectively;

FIGS. 4 a and 4 b show, in more detail, cross-sectional views of theexemplary convex and concave fluidic adaptive lenses of FIGS. 3 a and 3b, respectively, along with related support structures;

FIGS. 5 a and 5 b show two cross-sectional views of other exemplaryembodiments of fluidic adaptive lenses that maintain a constant outershape;

FIG. 6 shows, in simplified schematic form, a hydraulic circuit that canbe employed with respect to lenses such as those in FIGS. 3 a and 3 b;

FIG. 7 is a simplified flow chart showing exemplary steps of a procedurefor creating a hydraulic circuit such as that of FIG. 6 employing lensessuch as those in FIGS. 4 a-4 b;

FIG. 8 shows in schematic form a zoom lens system employing at least onefluidic adaptive lens;

FIG. 9 shows a cross-sectional view of an exemplary fluidic adaptivelens capable of being used to achieve a wide focal-distance tuningrange;

FIG. 10 is a graph showing how a focal length of the fluidic adaptivelens of FIG. 9 varies with fluidic pressure in one embodiment;

FIG. 11 a-11 d show in schematic form steps of an exemplary process forconstructing a lens structure utilizing fluidic adaptive lenses that canbe employed in a zoom lens system;

FIGS. 12, 13 a and 13 b show three cross-sectional views of otherexemplary embodiments of lens structures;

FIGS. 14 a-14 b, 15 a-15 c and 16 a-16 d show cross-sectional views ofexemplary embodiments of two-lens structures formed form variouscombinations of the lens structure shown in FIGS. 12, 13 a and 13 b.

FIG. 17 is a graph showing the variation of magnification provided by anexemplary zoom lens system, in accordance with one of the embodiments ofFIGS. 14-16, as a function of front lens power; and

FIG. 18 is a simplified flow chart showing exemplary steps of aprocedure for creating a two-lens structure such as those shown in FIGS.14 a-14 b.

DETAILED DESCRIPTION

Embodiments of the present invention concern the design and constructionof fluidic adaptive lenses, as well as the use of one or more suchlenses in a variety of environments and applications. Indeed,embodiments of the present invention include a variety of applicationsand environments in which one or more fluidic adaptive lenses can beemployed including, for example, eyeglasses, zoom lens systems,microscopes, video monitors, video recorders, optical recordingmechanisms, bar-code readers, systems with magnifying functions,surveillance equipment, security equipment, inspection equipment, agileimaging equipment, target tracking equipment, copy machines, scanners,cell phones, personal digital assistants (PDAs), notebook computers,telescopes, magnifying glasses, optometrist equipment, surgicalequipment, biometric equipment such as iris scanning equipment andfingerprint-scanning equipment, and other devices that require lenses.

At least some embodiments of the present invention relate generally tothe design and implementation of fluidic adaptive lenses, independent ofany particular application of such lenses. The present invention isintended to encompass a variety of different lenses, lens structures andlens systems that employ one or more fluidic adaptive lenses that arevariable in terms of optical characteristics, including a variety oflens types such as convex, concave, convex-concave, positive or negativemeniscus, plano-convex, plano-concave, bicovex and biconcave lenses.

Referring to FIGS. 1 a and 1 b, exemplary fluidic adaptive lensescapable of being implemented in a variety of environments andapplications such as those described above are shown in schematic form.FIG. 1 a more particularly shows a cross-sectional view of oneembodiment of a lens structure that can be implemented in any of thevariety of environments and applications described and/or referencedabove. As shown, FIG. 1 a comprises a lens membrane 110 a and twofluidic mediums 120 and 130. The lens membrane 110 a is shown in astress-free state. That is, the lens membrane 110 a is not shown to beelastically deformed by the fluidic medium(s) 120 and/or 130.

Turning to FIG. 1 b, the exemplary fluidic adaptive lens of FIG. 1 a isshown in a different configuration, in which the lens membrane, nowreferred to as a lens membrane 110 b, is elastically deformed. Thedeformation of the lens membrane 110 b is achieved by applying fluidicpressure via the fluidic medium 130 and/or releasing fluidic pressurevia the fluidic medium 120. One of skill in the art will recognizealternative deformations than that shown in FIG. 1 b, such as thoselisted above.

Lens Membrane

At least some aspects of the present invention pertain to thedeformation of lens membranes such as the lens membrane 110 b of FIG. 1b. To achieve desired deformation, the elastic properties of a lensmembrane can be of significance. Depending upon the embodiment, thedeformation of a lens membrane such as the lens membrane 110 b can occurvia any number of methods and systems including, for example, one ormore pressure vessels (not shown) that drive the fluid medium(s) 120and/or 130 into and out of one or more lens chamber(s) (not shown).Further for example, when a pressure vessel drives the fluidic medium130 into a lens chamber containing that fluidic medium, the lensmembrane 110 b then expands to an elastically deformed lens profilestate, such as the state shown in FIG. 1 b. When the pressure vesseldrives the fluidic medium 130 out of the lens chamber, the lens membrane110 b returns to its stress-free state, such as the state shown in FIG.1 a.

Various methods are possible for controlling the deformation of a lensmembrane such as the lens membrane 110 b via one or more pressurevessels. For example, a valve (not shown) can be used in conjunctionwith a pressure vessel to regulate the transfer of fluid into and out ofa lens chamber. Other devices that can be employed in conjunction with apressure vessel include, for example, a piezoelectric motor (not shown),a bellow (not shown), a solenoid switch (not shown), and other likedevices capable of regulating deformation of the lens membrane 110 b.The present invention is intended to encompass, in various embodiments,any of these methods and devices, as well as others that are known tothose of skill in the art.

In at least some embodiments, the lens membrane 110 b is designed topossess not only high flexibility but also a reasonably low springconstant so that the size, cost, and/or power consumption of thepressure vessel and any related control device are not limiting factors.

In at least some embodiments of fluidic adaptive lenses capable of beingused in compact fluidic zoom lens systems, an attractive material for alens membrane such as the lens membrane 110 b is polydimethylsiloxane(“PDMS”). Certain PDMS materials (e.g., Sylgard 184, Sylgard 182, Gelest1.41, Gelest 1.42, etc.) are optically transparent and can be stretchedto 300-700% of their stress-free states. Furthermore, the Young'smodulus for certain PDMS materials is on the order of 1 MPa. Forexample, a 4-5 mm diameter lens with a 60-100 μm thick PDMS lensmembrane made from Dow Corning Sylgard 1:10 (available from the DowCorning Corp. of Midland, Mich.) requires less than ±40 grams (˜0.4Newton) of force to achieve the full tuning range of the focal distance.The required force for a full tuning range of focal distance is severaltimes lower for PDMS than other types of optically transparent elastomersuch as polyurethane. Thus, in at least some circumstances, an opticallytransparent elastomer with a low Young's modulus such as PDMS is afavorable choice for small form factor tunable lens systems inaccordance with at least some embodiments of the present invention.

In addition to the characteristics discussed above, in at least someembodiments, the material of a lens membrane such as the lens membrane110 b is designed to possess a relatively high resistance to both UVradiation under sun light and water condensation when temperature dropsbelow the dew point. PDMS materials can satisfy these criteria.

In alternate embodiments of the present invention, materials other thanPDMS materials can be employed. For example, lens membranes such as thelens membrane 110 b can also be formed of silicone rubber. Preferably,the silicone rubber would be selected to have transparent or opticallyclear characteristics.

Fluidic Medium

A variety of different fluidic media can be utilized depending upon theembodiment including, for example, water, methanol, lens oil, saline,and air. At least some additional aspects of the present inventionpertain to the fluidic medium(s) (e.g., the fluidic medium(s) 120 and/or130), which are designed to possess not only desirable opticalproperties, but also both material and process compatibility with thelens membrane(s) with which they interact (e.g., the lens membrane 110b). In at least some embodiments, fluidic media with one or more of thefollowing characteristics are preferred: a relatively high index ofrefraction (e.g., to achieve high lens power and wide tuning range); lowattenuation over the wavelength spectrum of interest (e.g., wavelengthspectra of 430-700 nm or 400-1600 nm); a wide range of operabletemperatures (e.g. −20 degrees C. to >60 degrees C.); a wide range ofstorage temperatures (e.g. −40 degrees C. to 100 degrees C.); anextremely low (e.g., nearly zero) vapor pressure (e.g., to prevent lossof fluid by evaporation through the lens membranes, particularly wherethe lens membranes are gas permeable); and a chemical stability withrespect to the lens membrane and other fluidic chamber material(s).

For example, in at least some embodiments, the fluidic media can meetone or more of the following exemplary characteristics: the fluidicmedia can have an index of refraction of at least 1.3; the fluidicmedium can transmit at least 20% of an optical signal over a wavelengthspectrum that spans at least 200 nm; the fluidic medium is capable ofoperating over a range of temperature that spans at least 30 degreesCelsius (e.g., a range from −20 degrees Celsius to 60 degrees Celsius);the fluidic medium is capable of being stored over a range oftemperature that spans at least 30 degrees Celsius (e.g., a range from−40 degrees Celsius to 100 degrees Celsius).

Further, in at least some embodiments, other considerations also can betaken into account when selecting fluidic media including, for example,safety, biocompatibility and/or toxicity. Such considerations canpotentially outweigh shortcomings associated with index of refraction,vapor pressure, or other previously-mentioned design characteristics.For example, in conjunction with a PDMS lens membrane and a siliconerubber lens chamber, fluidic media such as water and methanol often maynot be preferred since they have relatively low indices of refractionand may be evaporated through a gas permeable lens membrane;nevertheless, other considerations such as safety and biocompatibilitymay render these fluidic media preferable in a given applicationnotwithstanding their shortcomings. Additionally for example, incircumstances where a lens system is used inside or close to a humanbody (e.g., contact lenses, implanted vision correction device(s) aftercataract removal, and/or other devices for use during medicalprocedures), fluidic media such as saline can be a preferred choice inview of considerations such as toxicity, safety and biocompatibility.This is the case even though the use of fluidic media other than salinecan potentially enhance device performance and device lifetime.

In some circumstances, fluidic media that comprise desirablecharacteristics such as those listed above can also comprisecharacteristics that destroy or damage certain types of lens membranessuch as PDMS lens membranes. For example, while a fluidic mediumincluding conventional lens oil can have both low vapor pressure and arelatively high index of refraction, such a fluidic medium willgenerally be incompatible with a PDMS lens membrane. This is because,over time, molecules associated with the oil in the fluidic medium maybecome incorporated into the polymer chains of the PDMS of the lensmembrane, thus making the PDMS lens membrane swollen or wrinkled.

Thus, in at least some embodiments in which PDMS lens membranes areemployed, it is advantageous to select fluidic medium(s) that will notdamage the PDMS lens membranes and will retain many of the desiredcharacteristics of those lens membranes as discussed above. In one suchembodiment, the fluidic medium(s) (e.g., the fluidic medium(s) 120and/or 130 of FIGS. 1 a and 1 b) include polyphenyl ether (“PPE”). Afluidic medium that comprises PPE is typically compatible with a PDMSlens membrane and a silicone rubber-based lens chamber. In furtherembodiments, alternative chemicals comprising similar properties to PPEcan be used as fluid media with PDMS lens membranes. Such chemicals caninclude, for example, thioethers benzene, and various ionic fluidsincluding, for example, 1-butyl-1-methylpyrrolidiniumtris(pentafluoroethyl)trifluorophosphate and 1-hexyl-3-methylimidazoliumtris(pentafluoroethyl)trifluorophosphate.

In at least some embodiments, the fluidic medium (or mediums) can be alens fluid containing a phenyl group, or more particularly a lens fluidcontaining a phenyl group and also having a molar molecular weightgreater than 200 g. In at least some additional embodiments, the fluidicmedium can be lens fluid LS5257 available from Nusil Technology LLC ofCarpinteria, Calif., or some other type of fluid included within thecategory of lens oils or polyphenyl ether fluids. In at least some suchembodiments, such a fluidic medium (e.g., a lens fluid containing aphenyl group, a lens fluid containing a phenyl group and having a molarmolecular weight greater than 200 g, or the lens fluid LS5257) is usedin combination with one or more PDMS lens membrane(s) and/or one or moreother transparent elastomer membrane(s). Notwithstanding the abovediscussion, a variety of other fluidic medium(s) are intended to beencompassed within embodiments of the present invention, including avariety of different fluidic medium(s) having a variety of differentcharacteristics in terms of molecular weight, viscosity, transparency,color, thermal expansion coefficient, etc.

Those skilled in the art will readily recognize that numerous variationsand substitutions can be made with respect to the above-describedembodiments of the present invention, their uses and theirconfigurations, to achieve substantially the same results as achieved bythe above-described embodiments. In particular, special considerationscan be required for the selection of the lens membrane, lens chamber,and fluid medium(s) for each specific application of the presentinvention. Accordingly, there is no intention to limit the invention tothe disclosed exemplary forms. Many variations, modifications andalternative constructions fall within the scope and spirit of thedisclosed invention as expressed in the claims.

Further, it should be understood that, whether any particular fluidicmedium is considered “safe”, “biocompatible”, “non-toxic” or otherwisesuitable for any particular application depends upon the purpose,application, the operational environment, and/or operationalcircumstances. The present discussion is not intended to imply thesuitability or unsuitability of any fluidic medium or other feature(s)of fluidic adaptive lenses for any particular purpose, application,operational environment or circumstances. Rather, when implementing afluidic medium or other feature for any given purpose, application,operational environment or circumstances, it should be consideredwhether the fluidic medium or other feature is suitable for thatpurpose, application, operational environment or circumstances.

Systems and Methods Using Lens Membrane(s) and/or Fluidic Medium(s)

The present invention is also intended to encompass a variety of aspectsrelating to the design and/or construction of fluidic adaptive lenses,as well as the use of one or more such lenses in a variety ofenvironments and applications such as eyeglasses, zoom lens systems andother applications such as those discussed above. FIGS. 2-7 generallyrelate to the design and implementation of fluidic adaptive lenses foruse in eyeglasses that are capable of providing dynamically-adjustablevision correction power. FIGS. 8-18 generally relate to the design andimplementation of fluid adaptive lenses and combinations of such lensesfor use in zoom lens systems that can be incorporated into a variety ofdevices such as, for example, cameras in cellular phones, and that arecapable of providing variable zooming capability without the need forcomplicated mechanical devices for physically moving multiple lensestoward or away from one another.

Although FIGS. 2-18 particularly relate to the design and implementationof fluidic adaptive lenses for use in eyeglasses and zoom lens systems,certain embodiments of the present invention are also intended toencompass the use of these or similar fluidic adaptive lenses in avariety of other applications and circumstances including, for example,a wide variety of other electronic and other devices such asmicroscopes, video monitors, video recorders, optical recordingmechanisms, bar-code readers, systems with macro (or magnifying)functions, surveillance equipment, inspection equipment, agile imagingequipment, target tracking equipment, copy machines, scanners, cellphones, personal digital assistants (PDAs), notebook computers,telescopes, magnifying glasses, optometrist testing equipment, and otherdevices that require lenses. Indeed, certain embodiments of the presentinvention relate simply to the design and implementation of fluidicadaptive lenses generally, independent of any particular application ofsuch lenses. Certain embodiments of the present invention are intendedto encompass a variety of different lenses, lens structures and lenssystems that employ one or more fluidic adaptive lenses that arevariable in terms of optical characteristics, including a variety oflens types such as convex, concave, convex-concave, positive or negativemeniscus, plano-convex, plano-concave, biconvex and biconcave lenses.

Referring to FIGS. 2, 3 a and 3 b, exemplary fluidic adaptive lensescapable of being implemented in eyeglasses are shown in schematic form.FIG. 2 shows an exemplary pair of eyeglasses 5 in which two fluidicadaptive lenses 6,7 are supported by frames 8. Turning to FIGS. 3 a and3 b, those figures show in cross-section two different types of lensesthat could be implemented as the lenses 6, 7 in the eyeglasses 5 of FIG.2. FIG. 3 a shows in general form a first fluidic lens 1 that can beused to correct hyperopia (farsightedness). As shown, the fluidic lens 1is a convex adaptive vision correction lens that contains a first medium20 that is a higher index fluid, a second medium 10 that is a lowerindex fluid, and a flexible membrane (or diaphragm) 30 that separatesthe two media. The flexible membrane 30 bends toward the lower indexside when the pressure of the higher index fluid is greater than that ofthe lower index fluid. In contrast to FIG. 3 a, FIG. 3 b shows thegeneral situation of a second fluidic lens 2 that can be used to correctmyopia (nearsightedness). As shown, the fluidic lens 2 is a concaveadaptive vision correction lens that contains a first medium 22 that isa higher index fluid, a second medium 12 that is a lower index fluid,and a flexible membrane (or diaphragm) 32 that separates the two media.The membrane 32 bends towards the higher index side when the pressure ofthe lower index fluid is greater than that of the higher index fluid.

The respective flexible membranes 30, 32 are deformed by the pressuredifferences between the respective pairs of media 10, 20 and 12, 22. Forexample, if the pressure on the higher index medium side is greater thanthat of the lower index medium side, the membrane will bend towards thelow index medium, as shown in FIG. 3 a, to form an effective convex lenscapable of correcting the hyperopia (farsightedness) problem. On theother hand, if a higher fluidic pressure exists on the low-index mediumside, the membrane will bend towards the high-index medium to form aneffective concave lens capable of correcting the myopia(nearsightedness) problem (see FIG. 3 b).

Turning to FIGS. 4 a and 4 b, exemplary fluidic lenses 36 and 46 areshown in cross-section, respectively. The lenses 36, 46 show in greaterdetail exemplary structures that can be employed as the convex andconcave adaptive vision correction lenses 1, 2 shown schematically inFIGS. 3 a and 3 b, respectively. As shown, the lenses 36 and 46 eachinclude a segment of transparent rigid material 31 and 41, respectively,a first fluidic medium 32 and 42, respectively, a second fluidic medium33 and 43, respectively, and a flexible membrane (or diaphragm) 34 and44, respectively. In the present embodiment, the second fluidic media33,43 are shown as air outside of the lenses 36,46, although thosefluidic media could be other fluids (gaseous or liquid) as well.

Additionally, each of the lenses 36, 46 includes a respective wall 37,47 that supports its respective membrane 34, 44 with respect to itsrespective transparent rigid material 31, 41. The walls 37, 47 encircletheir respective lenses 36, 46, which typically are circular oroval-shaped when viewed from the front of the lenses (albeit the lensescould have other shapes as well). The walls 37, 47 and the transparentrigid materials 31, 41 respectively form fluidic lens chambers. Thefluidic lens chambers (e.g., comprising walls 37, 47 and transparentrigid materials 31, 41), along with the membranes 34, 44, definerespective internal cavities 38,48 within which are the first fluidicmedia 32, 42. The walls 37, 47 of the fluidic lens chambers definerespective channels 39,49 by which the first fluidic media 32, 42 canenter and exit the cavities 38, 48. In certain embodiments, the walls37, 47 can be formed within the frames 8 of the eyeglasses 5. Also asshown in FIGS. 4 a and 4 b, arrows 35, 45 respectively represent thedirections of the flow (and/or pressure) of the media 32, 42 withrespect to the cavities 38, 48 that are appropriate for causing therespective lenses 36, 46 to become convex and concave, respectively. Asshown, the first fluidic medium 32 tends to flow into the cavity 38causing the membrane 34 to expand outward while the first fluidic medium42 tends to flow out of the cavity 45 tending to cause the membrane 44to contract inward.

By controlling the amounts of the first fluidic media 32, 42 that flowin and out of the cavities 38, 48 (which can depend upon the pressure ofthose media), the optical properties of the lenses 36, 46 can be varied.In particular, because in the present embodiment the second fluidicmedia 33, 43 are the air of the atmosphere, by applying a positivepressure to the first fluidic medium 32 (e.g., a pressure greater thanthe atmospheric pressure), the membrane 34 tends to expand outward asshown in FIG. 4 a, and by applying a negative pressure to the firstfluidic medium 42 (e.g., a pressure less than the atmospheric pressure),the membrane 44 tends to contract inward as shown in FIG. 4 b. Thus, thelenses 36 and 46 could in fact be the same lens, which in one state hasbeen configured as a convex lens and in another state has beenconfigured as a concave lens.

Although the lenses 36, 46 shown in FIGS. 4 a and 4 b are physicallycapable of operating as lenses (e.g., capable of causing light to befocused or to be dispersed), the structures of these lenses are notpreferred. Because the membranes 34, 44 in these embodiments are exposedto the outside atmosphere and outside environment, atmospheric pressurechanges, temperature changes and/or external impacts all can damage orchange the optical properties of the lenses 36, 46, such that the lensescan suffer from reliability, stability (including drift of the lenses'optical properties), and performance issues. Particularly in the mode ofthe concave lens 46 of FIG. 4 b, a fluidic lens chamber has to maintaina negative pressure relative to the atmosphere, which requires anair-tight design that is harder to achieve and keep stable than aleak-tight design for positive fluid pressure. Consequently, whilesuitable for some applications, the lenses 36, 46 can be used ineyeglasses primarily only when high viscosity and very low vaporpressure fluid is used as the liquid medium, which limits themanufacturability of the devices.

Two improved designs for fluidic adaptive lenses that are capable ofbeing employed as the lenses 6 and 7 of the eyeglasses 5, and that aremore robust and stable in operation than the lenses 36, 46 of FIGS. 4a-4 b, are shown in FIGS. 5 a and 5 b as lenses 50 and 60, respectively.To minimize the influence of the environment such as atmosphericpressure, the lenses 50, 60 employ rigid materials to form all (ornearly all) of the outer surfaces of the lenses. As shown, the lens 50of FIG. 5 a in particular includes two fluid lens chambers, while thelens 60 of FIG. 5 b includes three fluidic lens chambers.

Referring to FIG. 5 a, the lens 50 includes several components. First,the lens 50 includes a pair of transparent, rigid outer surfaces 51 (onboth sides of the lens) that are capable of keeping the outer shape ofthe lens unchanged as in the case of conventional solid lenses.Additionally, the lens 50 includes a flexible membrane (or diaphragm) 54positioned in between the rigid outer surfaces 51, and a pair of walls57 that support the membrane 54 in relation to the surfaces 51 a, b.Further, a lower index first fluidic medium 52 is contained within afirst cavity 58 defined by the membrane 54, and a fluidic lens chambercomprising the walls 57 a and the rigid outer surface 51 a. A higherindex second fluidic medium 53 is contained within a second cavity 59defined by the membrane 54, and a fluidic lens chamber comprising thewalls 57 b and the rigid outer surface 51 b. Also, the lens 50 includesfirst and second pairs of channels 55 and 56 that extend through thewalls 57 a, b, respectively, and respectively connect the first andsecond cavities 58 and 59 with fluid reservoirs (see FIG. 6). Inalternate embodiments, the channels 55, 56 can extend through thesurfaces 51 rather than through the walls 57. Also, while in FIG. 4 athere are a pair of channels 55, 56 leading to each of the cavities 58,59, respectively, in alternate embodiments there need be only onechannel or there could be more than two channels for one or both of thecavities (or, in some cases, only one of the two cavities might beaccessible by one or more channels).

The lens 50 can be employed either as the convex lens 1 of FIG. 3 a orthe concave lens 2 of FIG. 3 b depending upon the pressures of the firstand second fluidic media 52, 53. When the pressure of the first fluidicmedium 52 is greater than that of the second fluidic medium 53, themembrane 54 bends towards the cavity 59 and the device behaves as aconcave lens for myopia. When the pressure difference between the twochambers is reversed, the lens behaves as a convex lens for hyperopia.The pressures within each of the fluidic cavities 58, 59 can becontrolled by one or more mechanical or electromechanical actuator(s)that determine the pressure and direction and rate of flow into or outof the cavities by way of the channels 55, 56. The curvature of themembrane 54 is determined by the pressure difference between thepressures within the cavities 58, 59 (as well as possiblycharacteristics of the membrane itself).

Regardless of the particular magnitude/sign of the pressure differencebetween the first and second fluidic media 52, 53 within the first andsecond cavities 58, 59, and regardless of the atmospheric pressure, theouter shape of the lens 50 does not change since it is defined by therigid outer surfaces 51. Thus, in contrast to the lens designs of FIGS.4 a-4 b, the lens 50 of FIG. 5 a does not require the maintaining of anegative pressure to achieve a concave structure, so the structure doesnot need to be made air-tight. Because the viscosity of air and liquiddiffers by many orders of magnitude, it is far easier to achieve aleak-tight structure than an air-tight structure. Finally, since it isthe fluidic pressure difference that determines the curvature of themembrane 54, that lens property is independent of the atmosphericpressure that is equally applied to both fluidic media 52, 53. On theother hand, temperature changes will cause a very minor index change ofthe media through the thermo-optic effect, having an unnoticeable effectupon the eyeglasses 5.

As for the lens 60 shown in FIG. 5 b, this lens employs two transparentrigid outer surfaces 61 a-b, two flexible membranes 62 a-b positioned inbetween the outer surfaces 61 a-b, and three sets of walls 68 a-csupporting the membranes 62 a-b in relation to the outer surfaces 61a-b. The walls 68 a are positioned between the membrane 62 a and theouter surface 61 a, the walls 68 b are positioned between the membranes62 a-b, and the walls 68 c are positioned between the membrane 62 b andthe outer surface 61 b. The outer surface 61 a and the walls 68 a definea fluidic lens chamber, and the outer surface 61 b and the walls 68 cdefine another fluidic lens chamber.

The outer surfaces 61 a-b, the membranes 62 a-b, and the sets of walls68 a-c define three cavities. An inner cavity 70 is positioned betweenthe membranes 62 a-b. The outer cavities 69 a-b are positioned on theother sides of the membranes 62 a-b. A low index fluid 63 is providedinto the outer cavity 69 a, which is defined by the membrane 62 a andthe fluidic chamber comprising the walls 68 a and the outer surface 61a. Additionally, the low index fluid 63 is provided into the outercavity 69 b, which is defined by the membrane 62 b and the fluidicchamber comprising the walls 68 c and the outer surface 61 b. A highindex fluid 64 is provided into the inner cavity 70 defined by the walls68 b and the two membranes 62 a-b. Three fluidic channels 65, 66 and 67(or pairs or sets of channels) respectively connect the respectivecavities 69 a-b and 70 to fluid reservoirs (see FIG. 6), which can betwo (e.g., one for the high index fluid and one for the low index fluid)or three (e.g., one corresponding to each of the cavities) in number.

When the pressure of the high index fluid 64 is greater than thepressure of the low index fluid 63, the lens 60 behaves as a convex lensfor hyperopia. However, when the pressure difference is reversed, thelens behaves as a concave lens for myopia. Because the lens 60 has rigidouter surfaces 61 as in the case of the lens 50, the lens 60 has thesame advantages as the lens 50 in terms of stability, reliability andperformance. In alternate embodiments, the high index fluid can be inthe outer cavities 69 a-b and the low index fluid can be in the innercavity 70, or each of the cavities can contain fluid having the sameindex or having an index different than each of the other cavities.

Referring to FIG. 6, an exemplary hydraulic circuit 71 for controllingthe fluid pressure within a fluidic adaptive lens such as one of thelenses 36,46 of FIGS. 4 a and 4 b is shown. As shown, the hydrauliccircuit 71 includes a fluid reservoir 2 that is coupled by way of afirst valve 11 to one of the channels 39/49 of the lens 36/46.Additionally, the fluid reservoir 2 is also coupled, by way of aminipump 3 and a second valve 13, to another of the channels 39/49 ofthe lens 36/46. The minipump 3 (and possibly also the valves 11,13) iscontrolled by way of an electrical circuit 4. Also, a pressure sensor 9is coupled to a junction between the valve 11 and the lens 36/46,allowing for the pressure within the lens to be sensed. Based upon thecommands of the electrical circuit 4, the minipump 3 can operate to pumpfluid from the reservoir 2 into the lens 36/46 or, alternatively, pumpfluid from the lens back into the reservoir, assuming that the valve 13is in an open state. Depending upon the opening and closing of the valve11, fluid can also proceed from the lens back to the reservoir (orpossibly in the opposite direction as well).

The electrical circuit 4 controlling the hydraulic circuit 71 can takeany of a variety of forms including, for example, a microprocessor, aprogrammable logic device, a hard-wired circuit, a computerized deviceprogrammed with software, etc. The electrical circuit 4 can operatebased upon preprogrammed instructions or, alternatively, in response tocommands received from an outside source (e.g., in response topushbuttons pushed by a user, a received wireless signal, and othersignals). In the embodiment shown, the electrical circuit 4 can receivefeedback information from the pressure sensor 9 regarding the actualpressure within the lens 36/46, and base its operation upon thatfeedback information. Also, the mini-pump or actuator 3 can take on avariety of forms, or be replaced with a variety of other pumpingmechanisms. For example, the mini-pump or actuator 3 could be aperistaltic pump, a small frame-mounted pump, a piezoelectric actuator,a microelectromechanical system (MEMS) actuator, an electromagneticactuator, or a tunable integrated micropump such as that disclosed inU.S. provisional patent application No. 60/625,419 entitled “TunableFluidic Lenses With Integrated Micropumps” filed Nov. 5, 2004, which ishereby incorporated by reference herein. Also, pressure within the lens36/46 could be adjusted by way of a Teflon-coated set screw. The overallcircuit 71 might be battery-powered or powered in some other manner,e.g., by line power or solar power.

Although the hydraulic circuit 71 is shown in conjunction with one ofthe lenses 36, 46, this type of hydraulic circuit, or several of suchcircuits, could also be employed in relation to the lenses 50,60 ofFIGS. 5 a and 5 b and other fluidic adaptive lenses. For example, two ofthe hydraulic circuits 71 could be used in relation to the lens 50 withits two cavities, while two or three of the hydraulic circuits could beused in relation to the lens 60 with its three cavities. The hydrauliccircuit 71 is intended only to be exemplary, and certain embodiments ofthe present invention can encompass any of a variety of such circuits orother mechanisms that would be capable of adjusting the pressure of thefluid medium within the lens 36/46. For example, depending upon theembodiment, two valves and channels linking the cavity of the lens 36/46to the reservoir 2 need not be used and, in some such embodiments, onlyone channel constituting an inlet and an outlet with respect to thelens, and/or one valve, might be necessary.

Turning to FIG. 7, a flowchart 73 shows steps of an exemplary procedurethat can be used to manufacture hydraulic circuits such as the hydrauliccircuit 71 of FIG. 6 that employ fluidic adaptive lenses such as thelenses 36,46 of FIGS. 4 a-4 b. Similar procedures could be used tomanufacture hydraulic circuits for controlling fluidic adaptive lensessuch as those in FIGS. 5 a-5 b. As shown, upon starting the process, ina first step 23, an open-ended cavity is formed using a plastic polymermaterial such as polydimethylsiloxane (PDMS) or polyester. The typicaldimension of the cavity would range from about one millimeter to a fewcentimeters in diameter and from about one tenth to a few millimeters inheight. The surfaces defining the cavity can be understood to includeboth the rigid outer surface 31/41 and the wall 37/47 shown in FIGS. 4a-4 b. Although primarily formed by the plastic polymer material, therigidity of the cavity surfaces (particularly the portion of itssurfaces corresponding to the outer surfaces 31/41) could besupplemented by bonding the plastic polymer material to a thin (e.g.,150 μm) glass slide.

In a second step 24, a thin plastic polymer membrane is formed, againpossibly through the use of PDMS. The membrane is flexible (albeit notpermeable), such that the membrane can be used as a flexible diaphragmseparating regions in which different fluidic media having differentindices of refraction are positioned. The membrane thickness typicallywould be on the order of about 30 to 100 μm. Each of the cavity and themembrane can be fabricated using a soft lithography process such as thatdiscussed in “Soft Lithography” by Y. Xia and G M. Whitesides (Angew.Chem. Int. Ed. Engl. 37, 550-575 (1998)), which is hereby incorporatedby reference herein. Next, in a third step 25, the membrane formed instep 24 is bonded to the cavity formed in step 23 to form a closedcavity/chamber. The bonding could be achieved by way of an oxygen plasmasurface activation process, such as that discussed in “Three-dimensionalmicro-channel fabrication in polydimethylsiloxane (PDMS) elastomer” byB. H. Jo et al. (J. Microelectromech. Syst. 9, 76-81 (2000)), which ishereby incorporated by reference herein. When produced in large volumes,standard industrial processes such as injection molding and die castingcan be adopted to fabricate such lenses.

Then, in a fourth step 26, one or more channels 39/49 are formed alongthe wall/side of the lens 36/46 for the inlet and outlet of a fluidmedium into and out of the closed cavity. Although not necessary, thereare typically two channels per cavity, one of which constitutes an inletfor fluid when fluid pressure within the cavity is being increased andthe other of which constitutes an outlet for fluid when fluid pressureis being decreased. Although typically formed in the wall of the lens36/46, such channel(s) could alternatively be formed in the othersurfaces of the cavity, even in the membrane. Further, in fifth andsixth steps 27 and 28, respectively, the one or more channels areconnected to a fluid reservoir and to actuation components,respectively. As discussed above, the reservoir serves as a store offluid. The actuation components, which could include, for example, eachof the minipump 3, the valves 11,13 and the electrical circuit 4 shownin FIG. 6, cause fluid to be provided to the reservoir from the cavityand vice-versa. Finally, in a seventh step 29, a fluidic medium isintroduced into the cavity from the reservoir, and then the fabricationof the hydraulic circuit is complete, such that hydraulic circuitincluding the lens could then be mounted to/within the frame of a pairof eyeglasses such as those of FIG. 2.

Although FIG. 7 is directed toward the formation of a hydraulic circuitfor controlling a fluidic adaptive lens having one cavity such as thoseshown in FIGS. 4 a and 4 b and FIG. 6, the process could easily bemodified to allow for the creation of lenses such as those shown inFIGS. 5 a and 5 b and corresponding hydraulic circuits for controllingthe operation of such lenses. For example, the lens 50 could be formedby following the process of FIG. 7 and, additionally, forming a secondcavity at step 23 and attaching that second cavity in step 25 to theside of the membrane that was opposite to the side on which the firstcavity was attached. Additionally, the formation of a hydraulic circuitfor controlling the operation of the lens 50 would involve the formationof additional channels within the second cavity at step 26, theconnecting of additional reservoirs and actuation elements at steps 27and 28, and the introduction of a second fluidic medium at step 29.

Likewise, with respect to the lens shown in FIG. 5 b, in which there arethree cavities, two of which are between the two membranes 62, theprocess of FIG. 7 could be further modified to include additional stepswhere (1) a middle cavity is formed between two membranes (whichthemselves would typically be separated by a wall), (2) the twomembranes are then attached to the outer cavities, and (3) theappropriate formation of channels, connections to reservoirs andactuation components, and introduction of fluidic media areaccomplished. It should further be noted that, typically, when multiplecavities exist, at least two different fluidic media having differentrefractive indices will be introduced into the different cavities fromcorresponding different reservoirs. Any of a variety of fluidic mediacan be employed. For example, one of the media can be water (e.g.,deionized water) having an index of 1.3 and the other medium can be oilhaving a refractive index of about 1.6. Alternatively, other mediaincluding gaseous media such as air can be utilized. In alternateembodiments, the channels could also be formed prior to the combiningstep 25.

The use of fluidic adaptive lenses such as those discussed above withreference to FIGS. 2 a-4 b (and particularly those of FIGS. 5 a and 5 b)in eyeglasses provides numerous benefits. The fluidic adaptive lenses(and related hydraulic circuits) can be mass-produced as identicalunits, where the corrective power of each individual lens is set afterthe manufacturing process has been completed. Therefore the designoffers a fundamentally low cost solution from the production point ofview. Also, while optometrists can still determine the corrective powerof the fluidic adaptive lenses, the fluidic adaptive lenses also can bedynamically adjusted in terms of their corrective power by the eyeglasswearers themselves. This could significantly reduce the frequency withwhich eyeglass wearers might need to visit optometrists to obtain newprescriptions for eyeglasses. At a minimum, the time and costsassociated with obtaining eyeglasses with new prescriptions could besignificantly reduced since, upon visiting their optometrists for eyeexams, the optometrists could simply ““tune”” the wearers' existingglasses rather than order new glasses.

Further, even when eyeglasses are being replaced, patients will benefitfrom the use of tunable eyeglasses. Given the tunability of theirexisting eyeglasses, the patients will not need to suffer fromcompromised vision during the time period while they are awaiting theirnew eyeglasses. Additionally, because the fluidic adaptive lenses can bevaried continuously in their corrective power over a wide range, the useof these lenses makes it possible for optometrists to provide eyeglasswearers with lenses that more exactly suit the wearers' needs, insteadof merely selecting lenses that are the “nearest fit” to the wearers'needs from among a set of standardized lenses. Indeed, fluidic adaptivelenses could serve as a more graduated substitute for the solid-statelens set that optometrists use in determining their customers'prescriptions, and thereby allow optometrists to render more accurateprescriptions. Thus, fluidic adaptive lenses can be utilized inoptometrists' examination equipment. Additionally, fluidic adaptivelenses can eliminate any undesirable cosmetic effect for those who needbifocal lenses (or multi-focal lenses). Instead of utilizing bifocals, aperson can instead simply wear a single pair of eyeglasses that iscapable of being modified in its optical properties as necessary forperson's circumstance, e.g., based upon the flipping of a “dip switch”on the eyeglasses of the person.

To estimate the adjustment power of the fluidic adaptive lens 50 shownin FIG. 5 a, one can assume that the diameter of the lens is 20millimeters. Compared to the diameter change of a human pupil from about2 millimeters in sunlight to 8 millimeters in the dark, this lensdiameter is large enough for eyeglasses. Further, to estimate theadjustment power range of the fluidic adaptive lens 50, one can alsoassume that the low index medium is air with a refractive index of 1 andthe high index medium is water with a refractive index of 1.333. Using aray-tracing simulation program or the thin lens approximation for ananalytic solution, we have found that the maximum positive power andnegative power of the above fluidic adaptive lens is 12.8 D (diopters)and −12.8 D, respectively. Hence the total adjustment range for theadaptive corrective lens is from −12.8 D to 12.8 D, corresponding to anuncorrected visual acuity of 0.017 minute⁻¹ for hyperopia(farsightedness) and 0.022 minute⁻¹ for myopia (nearsightedness).

Further, if silicone oil is utilized as the high index medium(refractive index is about 1.5) and water is used as the low indexmedium, then the total adjustment power range for such adaptive lensesbecomes from 6.4 D to −6.4 D, corresponding to an uncorrected visualacuity of 0.036 minute⁻¹ for hyperopia and 0.042 minute⁻¹ for myopia.Also, if silicone oil is used as the high index medium and air is usedas the low index medium, then the total adjustment range for the fluidicadaptive lens becomes from 19.2 D to −19.2 D, corresponding to anuncorrected visual acuity of 0.010 minute⁻¹ for hyperopia and 0.016minute⁻¹ for myopia. Although these estimates are for a fluidic adaptivelens such as the lens 50 of FIG. 5 a, corresponding estimates for othertypes of fluidic adaptive lenses (e.g., the lens 60 of FIG. 5 b havingthree cavities 63, 64) can also be readily determined. Also, a widevariety of fluids of different indices can be employed other thansilicone oil, water and air to make the lenses and allow the lenses totake on a variety of optical properties, which can be easily analyzedbased on the principles of geometric optics. Likewise, the particularmaterials used to form the rigid outer surfaces, walls and flexiblemembranes of the lenses can include any of a variety of plastic, acrylicand other materials, and can vary from embodiment to embodiment.

From experimental observations, several other performance aspects offluidic adaptive lenses have also been determined. In particular, it hasbeen determined that the fluidic adaptive lenses allow for dynamiccontrol over each of the focal length, power, field-of-view, F-number,and numerical aperture (NA) as a function of fluidic pressure within thelenses. Also, it has been determined that there exists no cleardependence of the image quality provided by fluidic adaptive lenses onthe thickness of their membranes. Resolution and image quality ingeneral suffers as the focal length increases beyond a certain length,where the pressure of the fluid is low (which, among other things, canresult in gravity having a non-negligible effect on the shape of themembrane). This problem can be corrected by using membranes of greaterstiffness, at the expense of higher power consumption and maximum powerrequirement on the mini-pump and actuator. Assuming the use of lensesthat are generally circular in shape, the membrane (except when flat dueto not being flexed) tends to have a generally spherical shape, albeitthe membrane tends to be somewhat flatter near its center. In at leastone experimental fluidic adaptive lens having a PDMS fluidic chambercovered by a 60 μm PDMS membrane and bonded to a thin 150 μm glassslide, the relation between the focal length of the lens and the fluidicpressure within the lens was determined to be as follows: Ln(f)=−0.4859Ln (P)+7.9069.

Turning to FIG. 8, in accordance with certain embodiments of the presentinvention, two or more fluidic adaptive lenses can also be employed indevices that require multiple lenses. FIGS. 8-17 relate to variousimplementations of pairs of fluidic adaptive lenses to form zoom lenssystems (and, in particular, zoom lens systems that can be implementedin compact electronic or other devices). However, certain embodiments ofthe present invention are also intended to encompass other types ofmulti-lens systems employing more than two lenses, lens systems in whichone or more of the lenses are fluid adaptive lenses and other(s) of thelenses are conventional, solid (or other types of) lenses, and lenssystems that operate to perform other functions besides or in additionto the zooming functions that are performed by zoom lens systems.

Referring specifically to FIG. 8, a two-lens optical zoom system 78suitable for implementation in a compact electronic device such as acellular phone 79 is shown in a simplified schematic form. As shown, thezoom system 78 includes a front lens 72 (near an object) and a back lens74 (near an image of the object) that are separated by a distance(termed the “lens spacing”) d that is constant. In between the lenses,72 74, an optical medium 76 is typically situated. Depending upon theembodiment, the medium 76 between the two lenses 72, 74 can be any of avariety of optically transparent materials including, for example, air,glass, polymer, or anything transparent at the wavelengths of interest.For simplicity without losing generality, it can be assumed that both ofthe lenses 72, 74 are thin so that thin lens approximations can beapplied throughout the analysis. Each of the lenses 72, 74 has arespective imaging distance l₁ and l₂, respectively, the latter of whichis fixed. Zooming is achieved by varying the respective focal distancesf₁ and f₂ of the respective lenses 72, 74 (these and othernotations/variables used to describe characteristics of the two-lensoptical zoom system 78 are shown in FIG. 8).

Following the conventions of lens analysis, the variable Φ of a lens orlens system is defined as the power of the respective lens or lenssystem, which is also equal to the inverse (reciprocal) of the focaldistance f of the respective lens or lens system. Thus, while each ofthe lenses 72, 74 has its own values for Φ (e.g., Φ₁ and Φ₂,respectively), of particular interest for the two-lens optical zoomsystem 78 is an overall power of the system Φ_(τ). This quantity Φ_(τ)can be determined as a function of the respective powers Φ₁ and Φ₂ ofthe lenses 72, 74 and other parameters as follows:

$\begin{matrix}{\Phi_{2} = {\frac{1}{l_{2}} + \frac{1 + {\Phi_{1} \times l_{1}}}{{\Phi_{1} \times l_{1} \times d} + d - l_{1}}}} & (1) \\{\Phi_{\tau} = {{- \frac{d}{l_{2}}} \times \frac{\left( {\Phi_{1} + \frac{{\mathbb{d}{- 2}}l_{1}}{2{\mathbb{d}{\times l_{1}}}}} \right)^{2} - \frac{{\mathbb{d}^{2}{+ 4}}l_{1} \times l_{2}}{4{\mathbb{d}^{2}{\times l_{1}^{2}}}}}{\Phi_{1} + \frac{\mathbb{d}{- l_{1}}}{\mathbb{d}{\times l_{1}}}}}} & (2)\end{matrix}$

Equation 1 shows that for given object and image plane distances (l₁ andl₂; respectively) and the lens spacing d, the power Φ₂ of the secondlens 74 (as well as the focal distance f₂ of that lens) is uniquelydetermined by the power Φ₁ of the first lens 72 (as well as the focaldistance f₁ of that lens). Further, Equations (1) and (2) together showthat, for a given object conjugate, the overall power of this two-lenssystem (Φ_(τ)) can be adjusted by varying the powers of both lenses Φ₁and Φ₂ (or, alternatively, the focal distances of both lenses f₁ andf₂). In comparison, conventional designs using lenses with fixed focaldistances (e.g., solid lenses) have to rely on varying the lens spacingd and the image plane distance h to adjust the power of the system. Zoomratio (ZR), a parameter of merit for zoom systems, is defined as theratio of the maximal achievable power and the minimal achievable power(e.g., ZR=Φmax/Φmin, both of which are values of Φ_(τ)). From Equations(1) and (2), it is evident that, to achieve a high zoom ratio for givenobject and image plane distances, one should vary the focal distances asmuch as possible. These concepts and conclusions also hold for zoomsystems having more than two lenses.

Although, in principle, the concept of zooming via varying the focaldistances could be applied using any type of fluidic adaptive lens, itappears that no tunable or adaptive lenses reported to date have had awide enough tuning range to be practical. For example, the shortestfocal length ever demonstrated in liquid crystal adaptive lenses isabout 200 mm for a lens aperture of around 5 mm corresponding to anf-number of about 40, which is insufficient to allow appreciable zoomingeffect. Both theoretical analysis and ray tracing simulation indicatethat highly effective zoom systems can be achieved only if the focaldistances of the lenses can be tuned continuously from a distance muchgreater than the lens aperture to comparable to or shorter than theaperture. In other words, for a 5 mm lens aperture, one would need toacquire a range of focal length from several centimeters to 5 mm orless, a value 40 times less than the shortest focal length demonstratedin state-of-the-art liquid crystal adaptive lenses.

Further, an even higher zoom ratio can be obtained if not only the focaldistances of the lenses but also the “types” of the lenses can beadapted or converted between being positive lenses (having a positivefocal distance such as in the case of a convex lens) and negative lenses(having a negative focal distance such as in the case of a concave lens)and vice versa. Liquid crystal adaptive lenses are (at least at thepresent time) incapable of being changed in their type.

In accordance with an embodiment of the present invention, the two-lensoptical zoom system 78 (or similar systems) when equipped with fluidadaptive lenses can achieve sufficiently high zoom ratios, withoutvarying the lens spacing d separating the lenses 72, 74 within thesystem. By using fluidic adaptive lenses, not only can the focaldistances of the lenses 72, 74 be widely varied or tuned, but also thelenses can be changed or converted in their type. FIGS. 9-18 concernvarious structures that can be used for the lenses 72, 74 and zoomsystem 78 as well as a fabrication technique for such lenses. However,certain embodiments of the present invention are also intended toencompass other structures and fabrication techniques for creating zoomsystems by way of fluidic adaptive lenses that will be evident to thoseof ordinary skill in the art.

FIG. 9 shows exemplary component structures of a fluidic adaptive lens75 that can be used as each of the lenses 72, 74 of FIG. 8. As shown,the lens 75 includes a deformable/flexible membrane (or diaphragm) 81that is coupled to the rim of a cup-shaped structure 85 having afluid-containing lens cavity 82 that includes a fluidic medium 83. Oneor more (in this case, two) channels 84 through the cup shaped structure85 allow for the fluidic medium 83 to enter/exit the cavity 82 from/to afluid reservoir (not shown). When the fluidic pressure inside the cavity82 changes, the curvature of the membrane 81, and therefore the lensshape, changes as well, producing different focal distances. Using anelastic silicone-based material (e.g., PDMS) of low Young's modulus(e.g., 1 M Pascals) as the membrane 81, a large lens shape change can beachieved and even a lens type change can be achieved (e.g., from aconcave or flat surface to a convex surface and vice-versa) as thepressure inside the lens chamber varies (e.g., from a negative to apositive value relative to the pressure outside the chamber). To achievean even broader tuning range of focal distance, one can use a high indexfluid as the lens medium. Over the spectral range of visible light,highly transparent fluid having a refractive index of 1.68 iscommercially available.

FIG. 10 shows exemplary dependence of the focal distance f of the lens75 on the fluidic pressure with different lens media, namely, deionizedwater (n=1.33) and sodium chromate (n=1.50), assuming a 20 mm lensaperture. As shown, not only can the focal distance of the lens 75 bevaried by modifying the fluidic pressure, but also the type of lens(e.g., concave/negative or convex/positive) as indicated by negative orpositive focal distance values can be changed by modifying the fluidicpressure. It is noteworthy that minimal focal distances (20 mm for H2Oand 14 mm for sodium chromate in a positive lens and −17 mm for H2O and−6 mm for sodium chromate in a negative lens) shorter than the lensaperture are demonstrated. As the previous analysis indicates, the useof one or more fluidic adaptive lenses having both wide focal distancetuning ranges and lens type convertibility makes it possible to achievea high performance zoom system without the need for varying the lensspacing between the lenses.

The flexibility in the choice of the materials from which the lenses 72and other components of the zoom system 78 can be built, andparticularly the flexibility in the choice of materials that can be usedto form the medium 76, offers many possibilities for forming “integratedzoom lenses” and for wafer scale production of lenses and lens arraysfor zoom systems. FIGS. 11 a-11 d show schematically how an exemplarytwo-lens structure 90 capable of being employed within the two-lensoptical zoom system 78 could be fabricated at low cost in an exemplarywafer-scaled batch process. As shown in FIG. 11 a, a transparentsubstrate (e.g., a glass substrate or polymer substrate) 91 of properthickness is chosen and two wafers 92 patterned with respective cavities96 are fabricated first. The patterns defining the cavities 96 can beformed using a soft lithography process (as discussed above withreference to FIG. 7) or a molding process. Then, as shown in FIG. 11 b,the two wafers 92 are bonded to opposing sides of the substrate 91 in amanner such that the cavities 96 are open outward away from thesubstrate. Although each of the wafers 92 is shown as including twocavities 96, the wafers could also have one cavity or more than twocavities depending upon the embodiment.

Further, as shown in FIG. 11 c, two handle wafers 94 each with arespective membrane 93 deposited along a side thereof are provided. Thehandle wafers 94 provide mechanical support for bonding the membranes 93onto rims 95 (as well as, in this embodiment, onto intermediate points,within the cavities 96) of the wafers 92. The bonding process caninvolve oxygen plasma surface activation (as discussed above withreference to FIG. 7) or other appropriate processes. Finally, as shownin FIG. 11 d, the handle wafers 94 are removed from the membranes 93,leaving the completed two-lens structure 90, which includes a firstfluidic adaptive lens body 97 capable of facing an object and a secondfluidic adaptive lens body 98 capable of facing an imaging plane. Wheremultiple such two-lens structures 90 are created simultaneously on asingle wafer (e.g., a single wafer comprising several of the substrates91) by way of a batch process, such two-lens structures can be separatedfrom one another by dicing the wafer into individual two-lensstructures. Once an individual two-lens structure 90 is obtained, it canbe employed in the two-lens optical zoom system 78 by connecting thetwo-lens structure 90 to a fluidic system (e.g., to fluidic reservoirsand actuating components such as those shown in FIG. 6), and filling thecavities 96 with the lens media of choice. Although channels allowingfor fluidic media inflow/outflow with respect to the cavities 96 are notshown in FIGS. 11 a-11 d, it is to be understood that such channels areprovided (e.g., as slots or indentations in the rims 95 of the wafers92).

Of significance during the process shown in FIGS. 11 a-11 d is thatthere be good alignment between the cavities 96 used to form the firstand second fluidic adaptive lens bodies 97, 98. Because all of thematerials of the two-lens structure 90 are transparent and the patternsare formed on large sized wafers, one can use either a contact aligneror the Standard fixture of bonding machines (e.g., bonding machinesproduced by Karl Suss America, Inc. of Waterbury Center, Vt.) toroutinely achieve an alignment accuracy of a few micrometers. Assumingproper alignment of the cavities 96, the lens membranes 93 deposited onthe silicon handle wafers 94 can be bonded to the lens chambers withless alignment-concern. The process, discussed here allows fabricationof zoom lenses of nearly any size (e.g., from <0.1 mm to centimeters)for various applications.

By way of this process shown in FIGS. 11 a-11 d, two-lens optical zoomsystems can be achieved on a high volume, low cost manufacturing basis.However, certain embodiments of the present invention are also intendedto encompass a variety of other structures and fabrication processesthan those shown in FIGS. 11 a-11 d that can be used to create zoomsystems that utilize one or more fluidic adaptive lenses. Through themanufacture of such various structures by way of such varioustechniques, a variety of different fluidic lens structures other thanthe structures 90 can be obtained in order to meet different applicationrequirements. For example, while the two-lens structure 90 of FIGS. 11a-11 d would be adequate for some applications, it would nevertheless be(as in the case of the lenses 36, 46 of FIGS. 4 a-4 b) insufficientlyrobust for other applications due to the exposure of the membranes 93 tothe outside environment. In contrast, FIGS. 12-17 show additionalexemplary lens structures that can be attractive for implementation indevices where, to improve the robustness of the zoom systems, it isdesirable that the lens membranes not be directly exposed to the outsideenvironment or, even further, desirable that all lens membranes becontained within the inside body of the zoom system.

FIG. 12, 13 a and 13 b show additional fluidic adaptive lens structures100, 110 and 120 that can be employed as either of the lenses 72, 74 forconstructing two-lens optical zoom systems with better mechanicalrobustness than that afforded by the structure 90 of FIGS. 11 a-11 d.FIG. 11 in particular shows the lens structure 100 to include two outersurfaces 101 formed from a rigid material, a flexible membrane 102positioned in between the outer surfaces 101 and supported therebetweenby way of rigid walls 103. The outer surfaces 101, membrane 102 andwalls 103 surround and define first and second internal cavities 105 and106, respectively. The walls 103 also include fluidic channels 104 bywhich the first and second internal cavities 105, 106 formed between theouter surfaces 101 and the membrane 102 can be coupled to respectivefluidic reservoirs (or possibly the same reservoir) and actuationcomponents (not shown). The fluidic reservoirs provide first and secondfluidic media 107, 108, respectively, to the respective cavities 105,106. The first fluidic medium 107 typically (though not necessarily)differs in refractive index from the second fluidic medium 108, forexample, the first fluidic medium can have a lower refractive index thanthe second fluidic medium.

As for the lens structures 110 and 120 of FIGS. 13 a and 13 b, each ofthese lens structures includes a pair of flexible membranes 111positioned in between a pair of rigid outer surfaces 112 and supportedtherebetween by way of walls 113. In between the flexible membranes 111is defined an inner cavity 114, while in between each of the membranesand the corresponding neighboring one of the rigid outer surfaces 112 isdefined a respective outer cavity 115. The walls 113 contain inner andouter channels 116, 117 that respectively allow for fluidic media toenter/exit with respect to the inner cavity 114 and the outer cavities115, respectively. Typically, though not necessarily, the outer cavities115 receive the same fluidic medium while the inner cavity 114 receivesa fluidic medium different from that provided to the outer cavities 115.In the lens structure 110 of FIG. 13 a in particular, a first fluidicmedium 118 of lower refractive index is provided to the outer cavities115, while a second fluidic medium 119 of higher refractive index isprovided to the inner cavity 114. In the lens structure 120 of FIG. 13b, in contrast, the first fluidic medium 118 of lower refractive indexis provided to the inner cavity 114 while the second fluidic medium 119of higher refractive index is provided to the outer cavities 115.

The fluidic adaptive lens structures 100, 110 and 120 shown in FIGS. 12,13 a and 13 b each contain two media separated by one or two membranesdeformable by the pressure difference between the medium-containingcavities. For example, if the pressure in the higher refractive indexmedium cavity is greater than that in the lower refractive index mediumcavity, the membrane will bend towards the lower refractive index sideto form an effective convex lens. Conversely, if a higher fluidicpressure exists in the lower refractive index medium cavity, themembrane will bend towards the higher refractive index side to form aneffective concave lens. Thus, both the types of the fluidic adaptivelens structures (either negative or positive) as well as the focallengths of the fluidic adaptive lens structures can be modified/tunedvia dynamic control of the curvatures of the membranes of the lensstructures, which are determined by the fluidic pressure differencesbetween the two cavities on opposite sides of the membranes (andpossibly the characteristics of the membranes themselves). In the caseof the lens structures 110 and 120, the curvatures of the membranes areto some extent determined by the fluidic pressures in each of the threecavities rather than merely two of those cavities.

As discussed above, because the lens structures 100, 110 and 120 ofFIGS. 12, 11 a and 11 b have outer surfaces 101 and 112 that are rigid,the structures are more resilient to outside disturbances. It also makesthe fabrication process easier if these surfaces need to beanti-reflection coated to suppress undesirable light reflection.Further, because the outer surfaces 101, 112 are rigid, the externalshapes of the lens structures do not change even though the magnitudesand signs of the pressure differences between the cavities 105, 106, 114and 115 changes. Consequently, such lens structures 100, 110 and 120 canbe easily concatenated to form two-lens optical zoom systems such as thezoom system 78 as well as multiple-lens optical zoom systems (havingmore than two lenses) to achieve further increases in the zoom ratio.The pressure of each fluidic chamber/cavity can be controlled bymechanical, piezo-electric, electromagnetic, electromechanical, or otheractuators, such as those discussed above, and the curvature of eachmembrane is determined by the pressure difference between the twoadjacent chambers and the mechanical properties of the membrane(although, where a given lens has three chambers, the membranes'positions can be influenced by the pressures in all three chambers).While various liquids can be employed as the fluidic media 107, 108,118, 119, it should be understood from the above discussion that air (orsome other gas) can also be used as the low index medium. In the specialcase where air is used, a single-cavity fluidic adaptive lens can beconstructed by removing the cavities(s) for the lower refractive indexmedium.

FIGS. 14 a-14 b, 15 a-15 c and 16 a-16 d show exemplary two-lensstructures 122, 124, 126, 128, 130, 132, 134, 136 and 138 constructedwith various pairs of the fluidic adaptive lens structures 100, 110 and120 discussed with respect to FIGS. 12, 13 a and 13 b. As shown, each ofthe two-lens structures 122-138 includes a pair of the lens structures100, 110 or 120 that are separated by an intermediate optical medium 140that is positioned between the pair of lens structures. The opticalmedium 140 can take on a variety of forms, including forms such as thosediscussed above with respect to the substrate 91 of FIGS. 11 a-11 d, andthe medium can offer structural support for holding the pairs of lensstructures together as well as simply provide a transparent, opticallyconductive medium. More particularly, the two-lens structures 122-138combine the lens structures 100, 110 and 120 as follows. With respect tothe two-lens structure 122 of FIG. 12 a, this structure combines two ofthe lens structures 100 having the same orientation, such that thesecond fluidic medium 108 of one of the lens structures is positionedcloser to the optically conductive medium 140 while the first fluidicmedium 107 of the other of the lens structures is positioned closer tothe optically conductive medium. As for the two-lens structure 124 ofFIG. 14 b, this structure combines two of the lens structures 100 in anoppositely-oriented manner, such that the same fluidic medium (in theexample shown, the first fluidic medium 107) of each of the lensstructures 100 is positioned closer to the optically conductive medium140.

With respect to the two-lens structures 126, 128 and 130 of FIGS. 15 a,15 b and 15 c, respectively, these structures respectively combine twoof the lens structures 110 of FIG. 13 a, one of the lens structures 110of FIG. 13 a along with one of the lens structures 120 of FIG. 13 b, andtwo of the lens structures 120 of FIG. 13 b. With respect to thetwo-lens structures 132 and 134 of FIGS. 16 a and 16 b, respectively,these structures each combine the lens structure 100 of FIG. 12 with oneof the lens structures 110 of FIG. 13 a, where FIG. 16 a shows the lensstructure 100 in one orientation and FIG. 16 b shows the lens structure100 in an orientation opposite to that of FIG. 16 a. As for the two-lensstructures 136 and 138 of FIGS. 16 c and 16 d, respectively, thesestructures respectively combine the lens structure 100 of FIG. 12 withone of the lens structures 120 of FIG. 13 b, where FIG. 16 c shows thelens structure 100 in one orientation and FIG. 16 d shows the lensstructure 100 in an orientation opposite to that of FIG. 16 c. FIGS. 14a-14 b, 15 a-15 c and 16 a-16 d are only intended to show some exemplaryarrangements of the fluidic adaptive lens structures 100, 110, 120 toform exemplary two-lens structures that can be implemented in two-lensoptical zoom systems such as the system 78 discussed above, and otherarrangements of these and other fluidic adaptive lens structures areintended to be encompassed within certain embodiments of the presentinvention.

Turning to FIG. 17, performance characteristics of a functional fluidicadaptive lens optical zoom system designed and fabricated according tothe process discussed above with reference to FIGS. 11 a-11 d are shown.The system employs water as the high index medium, and has a 20 mmaperture and an image distance of 50 mm. As shown, at an image distanceof 50 mm, the ratio of the maximal to minimal magnification factor is4.6 and 4.2 for object distances of 250 mm and 1000 mm, respectively.This yields a zoom ratio of greater than 3.

More generally, to estimate the zoom ratio of the zoom system, one cancalculate zoom lenses with 3 mm and 1 mm apertures assuming water(n=1.333) as the high index medium and air as the low index medium. Fora 3 mm aperture zoom system with a lens spacing (d) of 8 mm and an imageplane distance of 5 mm, one obtains a zoom ratio of greater than 4:1.Such a zoom system has a maximal field of view (FoV) of around 45degrees. For a 1 mm aperture zoom system with a lens spacing of 8 mm andan image plane distance of 1.5 mm, one obtains a zoom ratio of greaterthan 5:1. The maximal field of view for such a zoom lens is about 17degrees. If desired, one can obtain a zoom ratio of greater than 10:1 atthe expense of the field of view, assuming a lens spacing of 8 mm and animage plane distance of 5 mm. Finally, since the tunable lenses possessa shape of a spherical surface of a tunable radius of curvature, itproduces about the same amount of aberration as solid-state sphericallenses. Such aberration can be corrected with one or more asphericalsurfaces, a practice widely used by the optical system design community.

Although the fabrication process shown with reference to FIGS. 11 a-11 dis not exactly applicable to the construction of the lens structures100, 110 and 120 shown in FIGS. 12, 13 a and 13 b or to the fabricationof the two-lens structures shown in FIGS. 14 a-14 b, 15 a-15 c, and 16a-16 d, a number of fabrication processes for such lens structures arepossible. For example, FIG. 18 provides a flow chart 140 showing oneexemplary process for constructing the lens structures 100 and one ofthe two-lens structures 122 making use of a pair of those lensstructures 100. Upon starting the process, in a first step 141, cavitiesare formed on two separate pieces of transparent substrate. The diameterof the cavities can vary from a few hundred micrometers to a fewcentimeters depending on the application, and the thickness (depth) ofthe cavities could be in the range of a few hundred micrometers to a fewmillimeters. In a second step 142, a thin polymer membrane is formed.The membrane thickness typically is in the range of tens of micrometersto 100 μm and the membrane behaves elastically under stress, such thatit can be used as a flexible diaphragm separating the cavities to befilled with media of different indices of refraction.

Next, in a third step 143, opposite sides of the polymer membrane formedin the second step are respectively bonded to the respective pieces ofsubstrate with the cavities formed in the first step to form two closedcavities, one on either side of the membrane. Then, in a fourth step144, one or more channels are formed in the side walls of each of thecavities to provide inlets/outlets for the fluidic media (in someembodiments, a given channel or hole can act as both an inlet and anoutlet, while in other embodiments, dedicated channels are providedspecifically as either inlets or outlets). Then, in a fifth step 145,the inlets and outlets are coupled to one or more fluid reservoirs(typically, in this case, first and second reservoirs for first andsecond fluidic media). Further, in a sixth step 146, one or moreactuation components are incorporated to control the flow of the fluidicmedia into and out of the cavities (e.g., by varying the pressures ofthe fluidic media). As discussed above, these actuation components cantake on any of a number of forms including, for example, fluidicmicropumps, piezoelectric actuators, micro-electro-mechanic-system(MEMS) actuators, teflon-coated set screws, or other forms of actuationcomponents, to control and set the pressure of each fluid chamber.

Next, in a seventh step 147, two fluidic media of different refractiveindices are provided into the respective cavities. For example, one ofthe media can be water having an index of 1.3 and the other medium canbe oil having a refractive index of about 1.6 (in alternate embodiments,the fluidic media can have the same refractive index). This completesthe construction of one of the lens structures 100. To form the two-lensstructure 122, steps 141-147 would be repeated a second time, shown asan eighth step 148, to generate a second of the lens structures 100.Once two of the lens structures 100 have been fabricated, the two lensstructures at a ninth step 149 can then be mounted to an optical mediumconstituting the optical medium 140 between the two structures as shownin, for example, FIGS. 13 a and 13 b. As noted above, the optical mediumcan be, for example, a solid transparent substrate of certain thickness(e.g. a glass wafer or a polymer substrate). Thus, the process offorming one of the two-lens structures 122, 124 of FIGS. 14 a and 14 bwould be complete.

Other processes for fabricating the lens structure 100 of FIG. 12 aswell as the lens structures 110 and 120 of FIGS. 13 a-13 b are alsopossible, as are other processes for fabricating the two-lens structures122-138 of FIGS. 14 a-14 b, 15 a-15 c and 16 a-16 d. Once constructed,the entire optical zoom systems using the two-lens structures can takethe form of cylindrical tubes of a few millimeters in diameter and aboutone centimeter long. Such devices can be conveniently attached to manyhandheld or pocket-sized devices. To the extent that a zoom system canbe made into a compact attachment capable of being retrofit tocommercial optical systems, many additional products such as eyeglassesor goggles with zooming functions are possible.

As discussed above, various embodiments of the present invention caninclude and/or be implemented in a variety of devices and systems usedfor a variety of applications and purposes. At least some embodiments ofthe present invention relate to the use of fluidic lenses that areintended for use in applications that involve the transmission ofvisible light. In at least some such embodiments, as discussed above,the fluidic lens contains fluid that is partially transparent over aspectral width of at least 200 nm. Additionally, at least some furtherembodiments of the present invention relate to the use of fluidic lensesthat are intended for use in applications that involve the transmissionof light at other ranges other than, or in addition to, the visiblespectrum. Such applications can include, for example, applicationsrelating to security, biometric (iris, fingerprint)scanning/identification, surgical equipment, bar-code scanning, etc. Insome such embodiments, light sources such as lasers or LEDs can beemployed to illuminate objects that are to be viewed via the fluidiclenses and, since such light sources often generate light that isconcentrated within relatively narrow optical spectra, in suchembodiments the fluidic lenses can operate (e.g., be at least partiallytransparent) with respect to light within narrow spectral ranges. In atleast some embodiments of the present invention, therefore, the fluidiclens can be at least partially transparent over only a spectral width ofat most 200 nm, or over a spectral width of at most some width less than200 nm.

Additionally, in some such embodiments where it is desired that thefluidic lenses transmit light at/within particular specific spectralranges, one can develop fluidic medium(s) for such lenses that arelimited to particular spectral ranges simply by adding particular dyesto the fluidic medium(s). For example, to limit transmission of lightthrough fluidic lenses to red light (within the visible light spectrum),one can simply introduce “red ink” to the fluidic medium to make thefluidic medium transmit only red light for desired applications.

Information and implementations relevant to the present invention areadditionally disclosed in U.S. patent application Ser. No. 11/683,141entitled “Fluidic Adaptive Lens Systems and Methods” filed on Mar. 7,2007, U.S. patent application Ser. No. 10/599,486, which is the U.S.national phase patent application of International Application No.PCT/US05/10948 entitled “Fluidic Adaptive Lens” filed on Mar. 31, 2005,and U.S. provisional application No. 60/558,293 entitled “FluidicAdaptive Lens” filed on Mar. 31, 2004, all of which are incorporated byreference herein. Further information and implementations relevant tothe present invention are disclosed in International Application No.PCT/US05/39774, entitled “Fluidic Adaptive Lens Systems with PumpingSystems,” filed on Apr. 11, 2005, and U.S. provisional application Ser.No. 60/625,419, entitled “Tunable Fluidic Lenses With IntegratedMicropumps” filed on Nov. 5, 2004, both of which are hereby incorporatedby reference herein.

It is specifically intended that the present invention not be limited tothe embodiments and illustrations contained herein, but include modifiedforms of those embodiments including portions of the embodiments andcombinations of elements of different embodiments as come within thescope of the following claims.

1. A lens device, comprising: a lens chamber including a plurality ofsurfaces, wherein at least one surface of the plurality of surfaces isoptically transparent; a lens membrane coupled to the lens chamber,wherein at least a portion of the lens membrane is flexible andoptically transparent, and wherein the lens membrane and the lenschamber define a first cavity; a fluidic medium positioned within thefirst cavity, the fluidic medium also being optically transparent; and acontrol device capable of controlling a parameter of the fluidic medium,wherein the fluidic medium is selected so as to transmit at least 20% ofan optical signal over a wavelength spectrum that spans no more than 200nm.
 2. The lens device of claim 1, wherein the fluidic medium transmitslight received from a light source including at least one of a laser anda light emitting diode.
 3. A system comprising the lens device and lightsource of claim 2, wherein the system is at least one of a securitysystem, biometric scanning or identification system, a piece of surgicalequipment, and a bar-code scanning system.
 4. The lens device of claim1, wherein the fluidic medium is formed from at least one of apolyphenyl ether material and a lens oil.
 5. The lens device of claim 1,wherein the fluidic medium includes lens fluid product model numberLS5257.
 6. The lens device of claim 1, wherein the fluidic medium isformed from thioethers benzene.
 7. The lens device of claim 1, whereinthe fluidic medium is formed from a medium selected from the groupconsisting of water, methanol, lens oil, saline, and air.
 8. The lensdevice of claim 1, wherein the fluidic medium is selected so as toachieve an index of refraction of at least 1.3.
 9. The lens device ofclaim 1, wherein the fluidic medium is capable of operating over a rangeof temperature that spans at least 30 degrees Celsius.
 10. The lensdevice of claim 9, wherein the range of temperature includes a rangefrom −20 degrees Celsius to 60 degrees Celsius.
 11. The lens device ofclaim 1, wherein the fluidic medium is capable of being stored over arange of temperature that spans at least 30 degrees Celsius.
 12. Thelens device of claim 11, wherein the range of temperature includes arange from −40 degrees Celsius to 100 degrees Celsius.
 13. The lensdevice of claim 1, wherein the fluidic medium is selected so as toachieve a vapor pressure of nearly zero.
 14. The lens device of claim 1,wherein the fluidic medium is selected so as to achieve chemicalstability with the lens membrane and the lens chamber, and wherein thelens membrane is formed from optically transparent silicone rubber. 15.A lens device, comprising: a lens chamber including a plurality ofsurfaces, wherein at least one surface of the plurality of surfaces isoptically transparent; a lens membrane coupled to the lens chamber,wherein at least a portion of the lens membrane is flexible andoptically transparent, and wherein the lens membrane and the lenschamber define a first cavity; a fluidic medium positioned within thefirst cavity, the fluidic medium also being optically transparent; and acontrol device capable of controlling a parameter of the fluidic medium,wherein the fluidic medium contains at least one phenyl group and has amolar molecular weight greater than 200 g.
 16. The lens device of claim15, wherein the fluidic medium is lens fluid product model numberLS5257.
 17. The lens device of claim 15, wherein at least one of thelens membrane and at least one surface of the lens chamber includespolydimethylsiloxane (“PDMS”).
 18. The lens device of claim 17, whereinthe lens membrane is made from at least one of PDMS and anothertransparent elastomer membrane material.
 19. The lens device of claim15, wherein the fluidic medium is lens fluid product model numberLS5257, and wherein at least one of the lens membrane and at least onesurface of the lens chamber includes polydimethylsiloxane (“PDMS”). 20.A method of fabricating a fluidic adaptive lens device, comprising:providing a lens chamber including a plurality of surfaces, wherein atleast one surface of the plurality of surfaces is optically transparent;affixing a lens membrane to the lens chamber, wherein at least a portionof the lens membrane is flexible and optically transparent and whereinthe lens membrane and the lens chamber define a first cavity;positioning a fluidic medium within the first cavity, wherein thefluidic medium is optically transparent; and providing a control devicecapable of controlling a parameter of the fluidic medium, wherein thefluidic medium contains at least one phenyl group and has a molarmolecular weight greater than 200 g.
 21. A lens device, comprising: alens chamber including a plurality of surfaces, wherein at least onesurface of the plurality of surfaces is optically transparent; a lensmembrane coupled to the lens chamber, wherein at least a portion of thelens membrane is flexible and optically transparent, and wherein thelens membrane and the lens chamber define a first cavity; a fluidicmedium positioned within the first cavity, the fluidic medium also beingoptically transparent; and a control device capable of controlling aparameter of the fluidic medium, wherein the fluidic medium compriseslens oil and has a molar molecular weight greater than 200 g.
 22. Amethod of fabricating a fluidic adaptive lens device, comprising:providing a lens chamber including a plurality of surfaces, wherein atleast one surface of the plurality of surfaces is optically transparent;affixing a lens membrane to the lens chamber, wherein at least a portionof the lens membrane is flexible and optically transparent and whereinthe lens membrane and the lens chamber define a first cavity;positioning a fluidic medium within the first cavity, wherein thefluidic medium is optically transparent; and providing a control devicecapable of controlling a parameter of the fluidic medium, wherein thefluidic medium has a transmission level of at least 20% of an opticalsignal over a wavelength spectrum that spans at most 200 nm and has amolar molecular weight greater than 200 g.
 23. A method of fabricating afluidic adaptive lens device, comprising: providing a lens chamberincluding a plurality of surfaces, wherein at least one surface of theplurality of surfaces is optically transparent; affixing a lens membraneto the lens chamber, wherein at least a portion of the lens membrane isflexible and optically transparent and wherein the lens membrane and thelens chamber define a first cavity; positioning a fluidic medium withinthe first cavity, wherein the fluidic medium is optically transparent;and providing a control device capable of controlling a parameter of thefluidic medium, wherein the fluidic medium has a transmission level ofat least 20% of an optical signal over a wavelength spectrum that spansat most 200 nm and has a molar molecular weight greater than 200 g. 24.A method of fabricating a fluidic adaptive lens device, comprising:providing a lens chamber including a plurality of surfaces, wherein atleast one surface of the plurality of surfaces is optically transparent;affixing a lens membrane to the lens chamber, wherein at least a portionof the lens membrane is flexible and optically transparent and whereinthe lens membrane and the lens chamber define a first cavity;positioning a fluidic medium within the first cavity, wherein thefluidic medium is optically transparent; and providing a control devicecapable of controlling a parameter of the fluidic medium, wherein thefluidic medium comprises a lens oil and has a molar molecular weightgreater than 200 g.